Wireless CAN-bus Bridge & concentrator(under construction)

Description

The WiCAN bridge & concentrator connects the physical CAN-bus to
a proprietary 802.15.4-based 2.4GHz radio network. Such a network can
consist of multiple bridges in order to join two or more CAN-bus segments
to each other. Additionally these devices function as the coordinator/concentrator
and physical CAN-bus gateway for our WiCAN wireless CANopen-based sensor- and
measuring devices.

In a given wireless CAN network, one device is the coordinator. The coordinator
manages the wireless network and can also be used to automatically apply the coordinator's
CAN-bus parameters to other bridges in the network.

Each of the bridge devices contains a CANopen implementation for the purpose of settings
and monitoring of the remote CAN-bus segment. This function can be disabled for non-CANopen
applications.

Plug & Play configuration

Out of the box, the device is configured to switch to OPERATIONAL state autonomously.
The node-ID is programmed to 1 for a coordinator node and to 2 for a 'slave' node. Their bit-rate
is preset to 250kbps. The automatic bit-rate detection kicks in when bus errors occur before any
valid messages have been received. After listening for all known bit-rates with no success, it reverts
to the preset value and stays there.

Node-ID preset at 1 for coordinator and 2 for bridge or end-device

Bit-rate predefined to 250kbps

Automatic switch to NMT state OPERATIONAL

TPDO1 (CAN-ID 0x180+$NODEID) sends RSSI and radio error counter upon change or every minute

All defaults can be changed using SDO or LSS configuration

Wireless performance & limitations

Connecting CANopen devices over a wireless link strips some of the reliability and
ruggedness features of the CAN bus protocol. Additionally, there are bandwidth limitations
that are less easily defined than with a wire-line approach. Use of more than 2 bridge
devices in a network results in multicast transmissions, which decreases effective bandwidth
proportionally to the number of bridges. When the wire-line feed bit-rate and message rate
exceed the available RF bandwidth, increased message latency may occur and ultimately
message loss.